Red feather gene

[Pajarita]

I found this fascinating but the thing is that, although the red pigment in parrot feathers has been linked to liver function (red suffusion been proof of it), they actually produce it in a completely different way than other birds to the point that they even have a special name for the pigment:psittacofulvins (see two studies about it below) I wonder why... because it is believed that the passerines are first cousins to the psittacines so, if they are more closely related to each other than other avian orders, why is it that they make this very important color differently? And how is it that although they don't find any concentration of psittacofulvins in parrots blood, the red coloration of the feathers is more saturated and brighter when fed a good diet rich in carotenoids? Also, if it's not on the blood, how does it translate that red suffusion happens from liver malfunction? Where is the link? Any ideas or has anybody found anything that would give us a clue?

http://www.theatlantic.com/science/arch ... ed/483467/

http://jeb.biologists.org/content/jexbi ... ith-ds=yes

http://www.public.asu.edu/~kjmcgraw/pubs/CBPB04.pdf

PS. Am I overwhelming you with links to studies like these or do you find them as interesting as I do?